Hi, I'm really benefiting from all the hard work here ( https://dvcs.w3.org/hg/editing/raw-file/tip/editing.html) and I think it's a great subject to address. Specifically, I've really found the JavaScript implementation ( https://dvcs.w3.org/hg/editing/raw-file/tip/implementation.js) a much needed tool for in-browser editing.
While working with that implementation, I noticed what I would call a bug. Specifically, line 2278 returns "undefined" for the "strikethrough" and "underline" commands, causing unnecessary "span" elements to wrap selections when executing some commands. I imagine either the "relevantCssProperty" for these two commands should be set to 'textDecoration' or perhaps there are implementation-specific issues and it should be set to "null". I hope this is the correct channel to provide this feedback; I did not see a better-fitting place to comment on the page. -Michael
